On the Acquisition Ambiguity for Galileo BOC(n,n) Modulated Signals

Binary offset carrier, BOC, modulated signals are at the moment candidates both for new civil (free) signal in GPS update and for part of the European Global Navigation Satellite System (GNSS) Galileo. They present better multipath mitigation and, potentially, better tracking characteristic but they have a multiple peak autocorrelation function. These secondary peaks could introduce problems both in acquisition and tracking stage, when usual approaches are employed at the receiver. Several possible strategies for mitigating lock ambiguities in acquisition and tracking, related to secondary peaks, have been presented in the past for BOC modulated signals. In this contribution we focus our attention on BOC(n,n) modulated signal, and analyze in detail the acquisition ambiguity problem versus the acquisition approach. We also present performance comparison (detection probability, probability of lock on secondary auto-correlation peaks) considering several test variables for the acquisition process. All the results are presented for the L1 Galileo signal format.